1. Technical Field
The present invention relates to a dual-rotor electric rotating machine which includes a stator and two rotors that are arranged so as to have the stator interposed therebetween.
2. Description of Related Art
Japanese Patent Application. Publication No. JP2003230262A discloses an electric rotating machine. This machine includes a rotor core (or field core) that is substantially U-shaped in cross section so as to have a pair of surfaces separated from and facing each other. On each of the surfaces of the rotor core, magnet magnetic poles are circumferentially arranged at equal intervals alternately with non-magnet magnetic poles. Further, a field winding is arranged at a position corresponding to the bottom of the substantially U shape of the cross section of the rotor core. Moreover, between the surfaces of the rotor core, there is interposed an annular stator core (or armature core). That is, this machine is configured as a dual-rotor electric rotating machine which includes a stator and two rotors that are arranged so as to have the stator interposed therebetween.
With the above configuration, it is possible to increase the total volume of air gaps between the stator and the rotors, thereby securing high performance while minimizing the size of the machine.
On the other hand, with the above configuration, it may be difficult to wind a stator winding (or armature winding) around the stator core. Moreover, during the winding process, the stator winding may interfere with the stator core, thereby damaging an insulating coat of the stator winding. Further, for preventing the above damage from occurring, it may be needed to lower the space factors of the stator winding in slots of the stator core.
In addition, since the stator winding and the field winding are surrounded by the stator core and the rotors, it may be difficult to effectively dissipate heat generated in those windings during operation of the machine. Consequently, it may be difficult to secure continuous high-output operation of the machine.